System for high resolution imaging and measurement of topographic and material features on a specimen

Abstract

A particle beam column for high-resolution imaging and measurement of topographic and material features on a specimen. The particle beam column includes a particle source for providing a primary beam along a primary beam axis for impinging on the specimen so as to release secondary electrons and backscattered electrons therefrom. The particle beam column also includes an objective lens for focussing the electrons so as to provide a radial dispersion of electrons relative to the primary beam axis, the radial dispersion of electrons including an inner annulus of backscattered electrons and an outer annulus of secondary electrons. The particle beam column still further includes a backscattered electron detector for detecting the inner annulus of backscattered electrons and a secondary electron detector for detecting the outer annulus of secondary electrons.

What is claimed is: 
     
       1. A particle beam apparatus for charge-free high-resolution imaging and measurement of topographic and material features on a specimen, the particle beam apparatus comprising: (a) a particle source for providing a primary beam along a primary beam axis, said primary beam impinging on the specimen so as to release electrons therefrom, said electrons including secondary electrons and backscattered electrons;   (b) an objective lens for focussing said electrons so as to provide a radial dispersion of said electrons relative to said primary beam axis, said radial dispersion of electrons including an inner annulus of backscattered electrons and an outer annulus of secondary electrons;   (c) a backscattered electron detector for detecting said inner annulus of backscattered electrons, said backscattered electron detector being located between said particle source and said objective lens;   (d) a secondary electron detector for detecting said outer annulus of secondary electrons, said secondary electron detector being located between said particle source and said objective lens; and   (e) an evacuated chamber for housing the specimen.   
     
     
       2. The particle beam column as in claim 1 wherein said objective lens includes an electrostatic objective lens. 
     
     
       3. The particle beam column as in claim 1 wherein said objective lens includes a magnetic objective lens. 
     
     
       4. The particle beam column as in claim 1 wherein said objective lens includes an electrostatic objective lens and a magnetic objective lens, said electrostatic objective lens deployed between the specimen and said magnetic objective lens so as to preserve the angular orientation of the secondary electrons. 
     
     
       5. The particle beam column as in claim 1 wherein said secondary electron detector and said backscattered electron detector are realized as a single electron detector. 
     
     
       6. The particle beam column as in claim 1 wherein said backscattered electron detector is deployed above said secondary electron detector relative to the specimen. 
     
     
       7. The particle beam column as in claim 1 wherein said backscattered electron detector is annular. 
     
     
       8. The particle beam column as in claim 1 wherein said secondary electron detector is split into angular sectors so as to provide pairs of signals for linewidth measurements of topographic features. 
     
     
       9. The particle beam column as in claim 8 wherein said secondary electron detector is split into angular sectors so as to distinguish topographic features which protrude from the specimen from those which are recessed into the specimen.